The cause of a temporary failure of Stark County's 911 emergency phone system last month has been identified.

The system was down, or at least partially down, from 9:26 a.m. to about noon on Oct. 6. Most who placed a 911 call during that span would have been greeted with a hyper-sounding busy signal.

It's the only time the system failed since it was put into place more than two years ago.

"But 99.9 percent is not good enough in 911," said Tim Warstler, director of the county emergency management agency, during a meeting Monday with county commissioners, safety workers and representatives of AT&T and Cassidian, a communications company that monitors the system around the clock.

An analysis by AT&T determined the problem was caused by a system hardware failure.

Jeroen de Witte, chief technology officer at Cassidian, said the company has never run across that same problem at any other location.

Stark's computerized system includes a primary server based at the sheriff's office and a secondary server in Canton. When the primary server malfunctions — as occurred on Oct. 6 — it's supposed to shut down and automatically switch operations over to the secondary, so no service lapse occurs.

Instead, the primary went into a non-responsive state.

The switch never occurred.

To compound matters, an attempt that morning to re-route 911 traffic to the Nimishillen Township emergency call center was short-circuited. AT&T later discovered that didn't work correctly because of previously undiscovered database omissions when Stark converted to its new system — omissions that were corrected the day after the failure.

"We are very fortunate this happened on a Sunday morning," said Jackson Township Fire Chief Tracy Hogue, noting that's historically a slow period.

De Witte said Cassidian employees will receive a technology bulletin, informing them to remotely switch Stark 911 over to the secondary server should an identical incident occur in the future.

Paul Stoffels and Andy Kopystynsky of AT&T said they are working with Warstler to add yet another layer of backup to Stark's 911 system. The tentative plan is to set up a reciprocal agreement with Summit County, so calls could be routed through there if Stark's system ever is completely down — and vice versa.